How to Make and Care for a Black Pine Bonsai? A Detailed Guide to the Latest Methods

The black pine (Pinus thunbergii) is an evergreen tree of the genus Pinus in the family Pinaceae. It is native to Japan and the southern coastal regions of Korea, and thrives in warm, humid maritime climates. It grows best in deep, loose, sandy soil rich in humus. It is not only an excellent plant for bonsai, but also a widely used, outstanding sapling in landscaping. Now let us take a look at how to make and care for a black pine bonsai!

Uses of the Black Pine Bonsai

The black pine bonsai has strong adaptability to its environment and can be grown in courtyards and on balconies alike. Its branches spread horizontally, its crown is like a canopy, its needles are deep green, it stays evergreen through all four seasons, and its form is ancient and elegant, so it can be enjoyed all year round. During the growing season, it is best placed outdoors in a spot with ample sunlight and good air circulation, and it should not be kept indoors for long periods. A black pine bonsai cultivated for many years has gnarled, vigorous old trunk and tangled, interlocking roots, displaying a wondrous dragon-and-phoenix posture and tenacious vitality, making it a fine specimen for home cultivation and enjoyment.

Habits of the Black Pine Bonsai

The black pine is mostly propagated from seed. Its germination rate is high, reaching 85%, and the seedlings grow vigorously. Collect the cones in mid to late October, sun-dry them to extract the seeds, winnow to clean the seed, and store them in bags over winter. Spring sowing should be done early. A nursery site with loose soil and good drainage, slightly acidic, is best; apply plenty of base fertilizer while preparing the ground, and disinfect the soil. Before sowing, soak the seeds in a 0.5% potassium permanganate solution for 2 hours, then soak them in 60°C warm water for a day and a night (letting it cool naturally). After removing them, spread them in a warm place, sprinkle water 1 to 2 times a day, and they can be sown after a week. They begin to sprout and emerge in mid to late April, and all will have emerged within 10 days. In the same year the seedlings can reach 10 to 15 cm tall. For potting, select sturdy 2- to 3-year-old saplings, then shape them further.

Making the Black Pine Bonsai

1. When digging them up, enlarge the digging area and be sure to keep as much soil as possible. Because black pines grow in sandy, stony soil on hillsides, there is little soil, and the winter weather is dry, so the soil holds little water and has poor cohesion; therefore, when digging, protect the soil around the roots as much as possible. The soil around the roots is rich in root fungi, which are symbiotic fungi of the black pine and are extremely beneficial to root growth. After digging, promptly wrap them simply in plastic bags to prevent the soil from being lost during transport, making transplanting easier.

2. When digging, be careful to protect the root system of the black pine. Start digging some distance away from the tree. First hollow out the soil around it, keep as much of the main root as possible, make the cut where the root is severed smooth, and cut away any rotten roots, avoiding damage to the root system as much as possible. This is especially true of the lateral roots and fibrous roots that the black pine sends into the sand and gravel; these roots are weaker, so keep them as long as possible and protect them particularly well when digging.

3. The black pine dug up should be planted in soil as soon as possible; the sooner the better, because a long delay will cause the roots to lose water and dry out, affecting survival. To prevent the roots from being buried too deep, you can plant high and set shallow, then add soil mounded on top to cover them. If there is no condition for planting in the ground, pot them promptly.

4. Potting the black pine is very important. Before planting, put a layer of crushed stone and tile pieces at the bottom of the pot to aid aeration and drainage, then fill the soil firmly around it. If there are large gaps in the soil, the roots are prone to freezing, so cover the pot with a straw curtain to prevent freezing. The best soil is the original soil from the mountain, or you can use a mixed soil made of coarse yellow sand, coal ash, and yellow clay in a ratio of 0.5:0.25:0.25. After potting, prune heavily in good time, because too much foliage will leave the roots unable to supply enough water and will consume a great deal of water and nutrients.

Caring for the Black Pine Bonsai

1. Environment: The black pine is cold-hardy and drought-tolerant and can be placed year-round on courtyard terraces, balconies, and platforms, in a spot with ample sunlight and good air circulation. But small bonsai should not be exposed to strong sunlight in midsummer. In winter it can overwinter in the open; it is best to bury the whole pot in a sunny, wind-sheltered spot. If overwintering indoors, the room temperature should not be too high, and it can be moved outdoors at Qingming Festival.

2. Watering: The black pine likes dryness and dislikes waterlogging, so do not water excessively; water only when the soil is dry, and water thoroughly when you do. Properly restricting water during the growing season can make the trunk thick and short and the needles short and small, adding ornamental value. In high summer temperatures, you can frequently spray water on the foliage, which benefits growth.

3. Fertilizing: The black pine tolerates poor soil and can grow normally even when the soil lacks fertilizer, and this also promotes a short trunk, dense branches, and short needles. But applying 1 to 2 times a suitable amount of thin, well-rotted cake fertilizer water during the growing season helps it grow vigorously and increases its resistance to pests and diseases.

4. Pruning: To maintain its graceful, ancient, and elegant tree form, the black pine bonsai must be pruned appropriately. During the growing season, pruning is mainly bud pinching, 3 to 4 times a year. When the new buds have elongated but have not yet produced needles, you can pinch off about 1/2 of each terminal bud; if the bonsai does not need to grow more branches, you can pinch off all the terminal buds. Branches that spoil the beauty of the tree form can be pruned during the dormant period.

5. Repotting: A black pine bonsai is generally repotted once every 3 to 5 years, preferably in February to March. When repotting, keep the original root ball intact as you tip it out, remove 1/2 of the old soil, cut away overly long roots as well as dead and rotten roots, and at the same time prune some unnecessary branches and foliage to keep the upper and lower parts of the root ball in balance. If the original pot is not large enough, switch to a slightly larger new pot; the planting method is the same as for potting.